Changbai Mountain Tianchi, also known as Baitoushan Tianchi, is located in Changbai Mountain Nature Reserve in the southeast of Jilin Province. It is the border lake between China and North Korea, with some water on each side. Tianchi is about 4400 meters long from north to south and 3370 meters wide from east to west. The elevation of the pool water is 2 189. 1 m, the deepest part is 373m, with an average of 204m, the water surface area is 9.82km2, and the perimeter is 13. 1 km.

From the fifth year of Song Qingyuan to the first year of Songjiatai (1199 ~1201), the Tianchi volcano eruption was the biggest eruption event in the world in recent 2000 years. At that time, volcanic ash was ejected as far away as the Sea of Japan and northern Japan. This volcanic eruption, a large number of lava gushed out, forming a basin in the crater. After a long time, the accumulated water became a lake and became Tianchi.

geologic feature

Changbai Mountain is located on the edge of East Asia continent, near the Pacific strong fold belt. As early as the Mesozoic era, from 200 million to 75 million years ago, there were many crustal changes and ancient rock formations were formed. The Mesozoic experienced hundreds of millions of years of wind and rain erosion, forming a series of intermountain basins. In the Cenozoic, it became a quasi-plain dotted with rolling hills.

With the Cenozoic Himalayan orogeny and the intermittent eruption of volcanoes, a series of fractures and uplifts occurred in the crust, and a large amount of magma in the deep underground erupted from the ground, forming a basalt platform.

Before the arrival of Quaternary, the crustal movement entered a new active period, and volcanic activity tended to be active, from the original fissure eruption to the central eruption. The ejected lava and various debris piled up on the lava plateau and platform around the crater, and a huge volcanic cone with Tianchi as the main volcanic passage was built.